Articulated ladder



July 7, 1964 M. E. GRAVES ARTICULATED LADDER Filed Dec. 12, 1962 INVENTOR.

MAURICE E. GRAVES BY way,

ATTYS.

United States Patent 3,139,949 ARTICULATED LADDER Maurice E. Graves, 2570 River Woods Road, Deerfield, Ill.

Filed Dec. 12, 1962, Ser. No. 244,129 3 Claims. (Cl. 182-36) This invention relates generally to devices for providing access to attics and the like, and more particularly, to: a new and improved construction of means for reaching such locations.

In many houses, and particularly in those embodying currently popular architectural designs, it is common practice to include an attic or to provide some storage space immediately under the roof of the house and yet not to provide a permanent stairway for reaching that space. Access normally is by way of a trap-door type opening located in the ceiling of a closet or hallway of the floor below. Since access to this space usually is not frequently necessary, means for the purpose is more often than not left to the ingenuity of the householder. One approach which has found some measure of success includes a rigid, counterweighted ladder which is mounted on the trapdoor is such a fashion that when the trapdoor is pulled downwardly the ladder is freed to slide down to the floor below. Such arrangements are not only expensive but also require considerable clearance above the trapdoor, which is not always available. Indeed, a homeowner may find that the only way to his storage space is by way of a conventional stepladder and with little room in which to so maneuver it or himself as to reach the access opening to the storage space.

It is a general object of the present invention to obviate deficiencies of prior devices through the provision of improved means for gaining access to attic storage areas and the like. It is a related object to provide such means which is readily adaptable for use in existing structures without significant modification thereof and which can, as readily, be utilized in new construction.

It is another object to provide an improved ladder which is usable With absolute safety, permits utilization within a very limited space, and which itself requires a minimum of storage space.

It is still another object to provide an improved articulated ladder construction that can be assembled and installed by even the average homeowner without need of professional skill or assistance.

It will be readily apparent to those skilled in the art that ceiling heights are not standardized and may be expected to Vary widely. A ladder or retractable stairway for one location would, therefore, be expected to be unusable in another. Thus, a further and an especially important object of the invention lies in the provision of meansfor attic and storage space access which not only permits of economical manufacture of readily available materials, but which also can be mechanized in individual units for purchase and assembly according to the dictates of the particularly contemplated installation.

The objects of the invention thus generally set forth, together with other objects and ancillary advantages, are attained by the construction and arrangement according to the following detailed description and the accompanying drawings, in which:

FIGURE 1 is an elevational view of an articulated ladder embodying the present invention and illustrating storage and use positions:

FIG. 2 is a perspective view of a step unit assembly illustrating one form of the invention;

FIG. 3 is a view taken substantially in the plane of line 3-3 of FIG. 1;

FIG. 4 is a perspective view similar to FIG. 2 but illustrating an alternative embodiment.

While the invention is susceptible of various modifications and alternative constructions, certain illustrative embodiments have been shown in the drawings and will be described in considerable detail. It is to be understood, however, that it is not intended to limit the invention to the specific forms disclosed. On the contrary, the intention is to cover all modifications, alternative constructions and equivalents falling within the spirit and scope of the invention as expressd in the appended claims.

Referring more particularly to the illustrative embodiments as depicted in the drawings, there shown is an articulated ladder assembly indicated generally at 10, embodying the present invention. The assembly includues a plurality of individual step units 11 hinged together to form a ladder, which can be stored in an attic or similar space and which can be easily pulled into position for use when desired.

An individual step unit 11 is shown in perspective in FIGURE 2. It includes a pair of side plates 14 with a tread 15 interposed between them. The side members 14 of each step unit can be conveniently fashioned of light metal, such as aluminum or magnesium alloys, generally in the form of a letter B. Each of the side members, as shown, includes a pair of spaced, parallel, longitudinal rails 16 interposed between which are spaced, parallel, transverse bars 17. Thus, the side members 14 are of parallelogram form.

In the illustrative embodiment of FIGS. 1-3, inclusive, each side member 14 is provided with a central transverse bar 18 parallel to the end bars 17 for supporting a tread 15. To this end, apertures 20 are formed in the member 18 for registration with apertures 22 formed in spaced bosses 23 which are integral with the bottom of the tread 15 at each of its ends. With the apertures 20 and 22 aligned, the tread and the side members are fastened together to form a rigid step unit 11, such that a horizontal step is provided in use.

To form a ladder, several step units are connected together in end-to-end relation. For this purpose, hinge links 25 are used. Each link is provided with an aperture 26 at each end thereof and complemental openings 27 are formed in the adjacent rear corners of the side members 14 of each step unit. Through aligned pairs of openings 26, 27, pivot bolts or rods (not shown) are inserted and the rear corners 28 of the side members 14 about the apertures 27 are rounded to define an articulated joint between each adjacent step unit. It-is important that the longitudinal spacing between the link apertures 26 corresponds to that between the openings 27 of the contiguous step units so that when the ladder is in extended or use position, the opposed surfaces of the adjacent cross members 17 of contiguous step units are engaged in face-toface contact with one another. It is also to be noted that the hinge links 25 are preferably fashioned from bar stock not only to be rigid but also to provide substantial surface area for engagement with the opposed surfaces of the side members 14. As thus formed the links, together with the connecting pivot bolts preclude relative lateral movement between contiguous step units 11.

Referring now to FIG. 4, an alternative construction of units 11 is illustrated. In this embodiment, fabrication of the side and tread members of each step unit of formable sheet material is contemplated, without sacrifice of strength, rigidity or other important aspect of the invention. As in the previously described embodiment each step unit comprises a pair of upright side members 34 and a transverse tread member 35. As shown, each side member 34 is formed, as by stamping, from a single piece of material such as cold rolled steel sheet. In overall outline it is of nonrectangular parallelogram form. Inwardly extending upper and lower transverse flanges 36 and 37, respectively, are provided which serve purposes comparable to those served by the transverse bars 17 of the first described form of the invention. To mount the tread 35 the upper flange 36 is formed with a pair of apertures 38 which are adapted to register with apertures 39 in the tread for the reception of appropriate fasteners such as bolts. Each tread 35, too, can be formed from sheet and is preferably of inverted channel-shaped cross-section, not only to provide adequate strength against sagging under load but also to insure rigidity of the assembled step unit. To this end the downturned tread flanges are terminated at right angles to the tread surface and the apertures 39 are so located with respect to tread ends that the flange ends are held in abutment with the juxtaposed portions of the surfaces of the side members when assembled with them. To further insure against relative sidewise skewing of the successive, sheet-formed step units when assembled, inter-fitting engagement between complemental elements is provided. To this end, flanking each upper flange 36, and extending upwardly with respect thereto, each of the side plates 34 is formed with tongues 40 which are offset slightly at 41 in a direction opposite to that of the flange 36. The right-hand tongue 40 (as seen in FIG. 4) is provided with an aperture 42. Similarly, the lower portion 45 of the side member 34 is offset, as at 47, a small amount and in a direction opposite to the offset 41, and an aperture 50 is provided in offset portion 45 for registration in line with the aperture 42 in tongue 40 to receive a pivot bolt and thus provide a hinge joint therebetween.

Since it is contemplated that headed fasteners are to be utilized to secure the tread 35 to the flanges 36 of the side members 34, the flanges 37 are provided with a complementally disposed pair of openings 49 of a size sufficently large to pass over the fastener heads. This permits the flange 37 to bear fully upon the juxtaposed portion of the tread 35.

It will be apparent then that when in use position the oppositely offset side member elements 40 and 45 and the tread fastener head, which is received in the flange apertures 49, effect full lateral stability, and with full flange-totread engagement a strong safe ladder is provided.

Again referring to FIG. 1 and in keeping with the invention, the ladder of either of the illustrative forms is easily stored when not in use. Thus, a simple runway, indicated generally at 50, is provided which comprises a humped track 51 formed of prallel rails 52. The rails can be fashioned simply of common lumber and, as shown, each includes longitudinal load-bearing elements 53 and side pieces 54 which extend slightly above the elements 53 to guide the step units in their movment therealong. Spacing of the rails 52 corresponds to the overall width of the assembled ladder. The track 51 is suitably supported by members 53 and is secured to the attic floor F adjacent the access opening 0. To prevent accidental withdrawal of the ladder so that it might unexpectedly fall, a hook 60 is conveniently provided on the uppermost step unit 11. This hook is adapted to engage a crossbar 61 which is extended transversely near the forward end of the track 51. When the ladder is pulled sufficiently far into extended position, the hook engages with the cross bar 61, and accidental collapsing of the ladder from the access opening is precluded.

After individual units of either of the illustrative embodiments have been assembled and connected together, the ladder can be put into use position simply by lifting it by the hinged side to a substantially vertical position and then moving it so that its upper end extends through the access opening and is placed in position adjacent the forward end of the runway 50. The ladder is then slowly lowered so as to engage the safety hook 60 with the cross rod 61 at the forward end of the runway.

To move the ladder from its use position into its storage position, one simply stands facing it and grasps the sides of the ladder or the treads, as may be convenient, and lifts the ladder slowly along the angle of inclination. As lifting movement proceeds, the hook 60 becomes disengaged from the cross rod 61, and as the lower extremity of each step reaches the first angle in the runway, that step falls backward onto the rails 51. This continues successively for each step, and, by the time the user has raised the ladder upwardly as high as he can comfortably reach, the uppermost step units will have traversed the hump in the runway and the ladder, by its own weight, will remain in the position into which is has been raised. It will be apparent that a short rod equipped with a hook, or some similar device, will enable the user to complete the raising operation until the lowermost extremity of the ladder has passed through the ceiling opening 0.

To move the ladder from its stored position upon the runway 50, the reverse of the above operation is performed; thus, the ladder is pulled forwardly and downwardly until the user can comfortably reach it. The user then grasps the sides and it can then be lowered until its lowermost extremity engages the floor G. As withdrawal movement continues, the safety hook 60 approaches the cross rod 61 and complete withdrawal is precluded when the two engage.

From the foregoing, it will be apparent that a ladder embodying the features of the present invention not only permits of utilization in locations where available use and storage space is limited, but its particular construction and arrangement insures a safe and strong assembly which becomes even more firm when Weight is placed upon its treads. Not only can the instant articulated ladder be economically fabricated from readily available materials, but it permits of unit merchandising for purchaser assembly and installation. The unit construction permits utilization of only the exact number of step sections to efiect a ladder length commensurate with the particular access height to be traversed. Once assembled and installed only minimum effort is required for moving the ladder between its operative and its storage positions.

I claim as my invention:

1. An articulated ladder comprising, in combination, a plurality of rigid step units having transversely pivotal connection at their upper and lower rear corners to adjacent like units, each of said units including parallel side members defining opposed upper and lower support surfaces for engagement with oppositely disposed support surfaces of adjacent like units and which surfaces are disposed in a generally horizontal plane when the ladder is in use, and having a tread secured between said side members associated storage means for said ladder including an overhead supporting frame defining a track upon which the side members of said step units rest during storage and which is traversed by said side members during movement of said ladder into and out of storage condition, said track having a hump near the ladder receiving end thereof and sloping downwardly therefrom for insuring articulation between adjacent units when said ladder is traversed thereover.

2. In combination, an articulated ladder comprising a plurality of relatively rigid step units hinged to adjacent units, each of said units comprising parallel side members having opposed parallel surfaces the upper and lower ones of which define support surfaces disposed in a horizontal plane when the ladder is in use, and a tread secured between pairs of said side members to complete said unit, and associated storage means for said ladder including an overhead supporting frame having a track comprising a pair of rails disposed thereon for receiving and storing said ladder, said track being humped near the ladder receiving end thereof and sloping downward therefrom for insuring the articulation of said unit relative to adjacent units when said ladder is urged into storage, a cross member extending between said rail portions near the ladder receiving end thereof, and means at the uppermost unit of said ladder for engaging with said cross member for securing the top of said ladder to said storage means when said ladder is in use to prevent accidental complete withdrawal.

3. A step unit adapted to be joined with like step units to form an articulated ladder, said unit comprising a pair of parallel side members, each of said members having oppositely offset upper and lower portions and including upper and lower inturned flanges, a horizontally disposed tread extending between said side members, and means for rigidly securing said tread to corresponding ones of said flanges on each of said side members, each of said side members having provision for transverse pivotal connection with the side members of like step units at the rear corners of said upper and lower offset portions for interfitting engagement of said offset portions when connection is effected with adjacent like units to form a ladder thereby providing longitudinal and lateral stability when in use.

References Cited in the file of this patent UNITED STATES PATENTS 512,322 Powers Jan. 9, 1894 2,419,321 Lopes Apr. 22, 1947 2,629,532 Tupper Feb. 24, 1953 3,042,143 Silen July 3, 1962 10 3,070,188 Scruby Dec. 25, 1962 FOREIGN PATENTS 701,738 Germany Jan. 22, 1941 

2. IN COMBINATION, AN ARTICULATED LADDER COMPRISING A PLURALITY OF RELATIVELY RIGID STEP UNITS HINGED TO ADJACENT UNITS, EACH OF SAID UNITS COMPRISING PARALLEL SIDE MEMBERS HAVING OPPOSED PARALLEL SURFACES THE UPPER AND LOWER ONES OF WHICH DEFINE SUPPORT SURFACES DISPOSED IN A HORIZONTAL PLANE WHEN THE LADDER IS IN USE, AND A TREAD SECURED BETWEEN PAIRS OF SAID SIDE MEMBERS TO COMPLETE SAID UNIT, AND ASSOCIATED STORAGE MEANS FOR SAID LADDER INCLUDING AN OVERHEAD SUPPORTING FRAME HAVING A TRACK COMPRISING A PAIR OF RAILS DISPOSED THEREON FOR RECEIVING AND STORING SAID LADDER, SAID TRACK BEING HUMPED NEAR THE LADDER RECEIVING END THEREOF AND SLOPING DOWNWARD THEREFROM FOR INSURING THE ARTICULATION OF SAID UNIT RELATIVE TO ADJACENT UNITS WHEN SAID LADDER IS URGED INTO STORAGE, A CROSS MEMBER EXTENDING BETWEEN SAID RAIL PORTIONS NEAR THE LADDER RECEIVING END THEREOF, AND MEANS AT THE UPPERMOST UNIT OF SAID LADDER FOR ENGAGING WITH SAID CROSS MEMBER FOR SECURING THE TOP OF SAID LADDER TO SAID STORAGE MEANS WHEN SAID LADDER IS IN USE TO PREVENT ACCIDENTAL COMPLETE WITHDRAWAL. 